now there is a pgit executable, and a package. That way, they are easier to use, especially
by other assemblies
Intermediate commit: all that's left is to convert the submodule command syntax to the one of
argaprse.

However, it showed that this project still uses tabs instead of spaces, which requires a fix
Converted tabs to spaces
Reorganized arguments to work with argparse, first working operation is 'submodule query'
add operation was fixed
'remove' operation is working once again.
Fixed move operation; print replaced with log where appropriate
'update' mode now works as well
Selective submodule update improved such that individual ones may be specified, and be pulled.
Previously this wasn't working, which kind of made the feature unusable.